MOULDING AND CASTING PIG IRON, ETC. log
ter,'1 as shown at Fig. 30, and in the hands of the man at the left in Fig. 34, is then quickly placed with pressure so as to be bedded into the main runner, as seen at B, Fig. 24. A few moments before this is done a man with a ravel, as seen at Fig. 34, pulls away the mound of sand, closing the connection from the " iron runner " to the " sow," as seen at C and D, Fig. 24, also at E, Fig. 29, to make an opening, as seen at F, Fig. 24. The top level of the pig beds should be below the level of the bottom of the main runner in order that all the metal may be drained from the main runner; and, again, the pig beds should not be too far below the level of the bottom of the main runner, as this would cause the metal to rush from the main runner to the sow with a force very liable to cut up the sand where the metal would strike the bottom • level, or wash away the cores between the pigs. The distance sought for is about that shown in the cuts, Figs. 28 and 29. If the moulder would consider trying to make a mould with what is generally termed a medium grade of bank sand, having the life pretty well burned out of it, he would then be in a position to understand how easily a rush of metal could cut ' up a pig bed of moulds, and the necessity for having certain conditions prevail, even if it is only 'f pigs '' that are being moulded and cast. As the metal flows down the runner, much of the sand floats with the iron; but as pigs are not finished, or condemned, if they are a little rough on their surface from dross or sand, there are no serious objections as long as it is not sufficient to impede its passage to the pigs. At H, Fig. 29, is seen the " ravel'1 as it is placed in the sand ready to make an opening to admitt it struckat the regular notch. It is often surprising how rapidly, as about 75 per cent of the heat generated from the solid fuel is utilized. This is attained where one ton of coke will produce one ton of iron; and Sir........................ 2,720 "